With the gain in popularity of open-plan office design and the engineering efforts to achieve acoustical comfort for building occupants, a majority of workers still report dissatisfaction in their workplace environment. Office acoustics influence organizational effectiveness, efficiency, and satisfaction through meeting appropriate requirements for speech privacy and ambient sound levels. Implementing a sound masking system is one method of achieving privacy goals. Although each sound masking system may be tuned for its specific environment, the use of random steady state electronic noise has essentially remained the primary approach for decades.
One goal of sound masking is speech privacy. Speech privacy affects both the talker and the listener. On the part of the talker, speech privacy becomes an issue of confidentiality. On the part of the listener, speech privacy ensures the mitigation of acoustical distraction and annoyance, thus facilitating a more concentrative environment. Factors that affect speech privacy are room absorption factors, speech effort, talker's orientation, privacy expectations, background noise, noise reduction of common constructions, barrier attenuation (i.e., partial height workstation barriers), and source to listener distance.
Traditionally, sound masking systems are installed as speaker arrays placed in the plenums above suspended ceilings pointing up towards the roof deck. This configuration allows for a more even distribution of sound. It is important that building occupants cannot localize the source of the masking sound. The masker is most successful when it has complete spatial and temporal uniformity in the room. The overall level is also important. Industry standards suggest a range between 40-45 dBA for an overall sound pressure level. The masking spectrum typically ranges from 100-5,000 Hz, or sometimes from 800-8,000 Hz and possesses suggested “roll-off” values in dB level per ⅓rd octave frequency band.
As noted, in most cases, the signal or sound source for commercially based sound masking systems is a random, steady state electronic noise. While design engineers have offered dynamic solutions to improve satisfaction in the workplace environment, the sound masking signal has largely remained the same for over 40 years.